Create many records in one call

Runs the sample. Generated for this page; it reads the connection string from the environment and first remakes the sample database from sample-schema.json.

using ArxSamples.MongoDb;
using ArxSamples.MongoDb.Operations.CreateMultiple.Basics;

// The connection string comes from the environment, never from the code (see "Configure the connection").
var connectionString = Environment.GetEnvironmentVariable("ARX_SAMPLES_MONGODB")
    ?? throw new InvalidOperationException("Set the ARX_SAMPLES_MONGODB environment variable to your MongoDB connection string.");

var dbContext = new SampleContext(connectionString);

// Every run starts from the sample data: this deletes and makes again what sample-schema.json lists
// (save the file in the project folder, see Get started).
await dbContext.Direct.ResetAsync();

await new Basic1_CreateManyRecords().RunAsync(dbContext);

The sample, as it is in the repository.

using ARX.SDK;
using ARX.SDK.MongoDb.Services;
using ARX.SDK.Services;

using static ArxSamples.MongoDb.SampleOutput;

namespace ArxSamples.MongoDb.Operations.CreateMultiple.Basics;

/// <summary>
/// Many documents in one call, all or nothing, with one id per entity in list order, in two scenarios: the call that
/// stores them all, and the call that stores none because one of them fails.
/// </summary>
/// <remarks>
/// CreateMultiple runs in a transaction, which MongoDB offers on a replica set (one node is enough) or a sharded
/// cluster. On a standalone server it is refused rather than half done.
/// </remarks>
public sealed class Basic1_CreateManyRecords : ISample
{
    public string Name => "create-multiple-basics-1-create-many-records";

    public string Title => "Create many records in one call";

    public async Task RunAsync(SampleContext dbContext)
    {
        await Scenario1_AllStoredAsync(dbContext.Service);

        await Scenario2_OneFailsAndNoneIsStoredAsync(dbContext.Service);
    }

    /// <summary>1. Three accounts in one call: the ids come back in the list's order.</summary>
    private static async Task Scenario1_AllStoredAsync(ArxMongoDbService service)
    {
        Step("1. All stored");

        var accounts = new List<ArxEntity>();

        foreach (var (name, number) in new[] { ("Alpine Ski House", "ACC-M101"), ("Blue Yonder Airlines", "ACC-M102"), ("Coho Winery", "ACC-M103") })
        {
            var account = new ArxEntity("account");
            account["name"] = name;
            account["account_number"] = number;
            accounts.Add(account);
        }

        IReadOnlyList<ArxRecordId> ids = await service.CreateMultipleAsync(accounts);

        Show($"created {ids.Count} accounts, the first {ids[0].AsString()}");

        /* ===========================================================
         * [DIRECT QUERY CHECK]
         * -----------------------------------------------------------
         * db.account.find({ account_number: { $in: ["ACC-M101", "ACC-M102", "ACC-M103"] } })
         * -- Expect: 3 documents.
         * ===========================================================
         */
    }

    /// <summary>2. The second account repeats an account number (a unique index): none of the three is stored.</summary>
    private static async Task Scenario2_OneFailsAndNoneIsStoredAsync(ArxMongoDbService service)
    {
        Step("2. One fails, none is stored");

        var first = new ArxEntity("account");
        first["name"] = "Fabrikam Inc.";
        first["account_number"] = "ACC-M104";

        var repeated = new ArxEntity("account");
        repeated["name"] = "Fabrikam again";
        repeated["account_number"] = "ACC-M104";

        var third = new ArxEntity("account");
        third["name"] = "Graphic Design Institute";
        third["account_number"] = "ACC-M105";

        try
        {
            await service.CreateMultipleAsync(new[] { first, repeated, third });
        }
        catch (ArxDatabaseException exception) when (exception.Code == ArxErrorCode.UniqueViolation)
        {
            ShowError(exception);
        }

        /* ===========================================================
         * [DIRECT QUERY CHECK]
         * -----------------------------------------------------------
         * db.account.find({ account_number: { $in: ["ACC-M104", "ACC-M105"] } })
         * -- Expect: no documents.
         * ===========================================================
         */
    }
}

  > 1. All stored
      created 3 accounts, the first 6af533c9162ec0b1c7534aa3
  > 2. One fails, none is stored
      caught ArxDatabaseException: ARX3001 UniqueViolation: CreateMultiple on 'account': a record with the same value in unique index 'account_number_1' already exists.